In history and heraldry, a cadet branch consists of the male-line descendants of a monarch or patriarch's younger sons (cadets). In the ruling dynasties and noble families of much of Europe and Asia, the family's major assets—realm, titles, fiefs, property and income—have historically been passed from a father to his firstborn son in what is known as primogeniture; younger sons—cadets—inherited less wealth and authority to pass to future generations of descendants.

In families and cultures in which this was not the custom or law, as in the feudal Holy Roman Empire, equal distribution of the family's holdings among male members was eventually apt to so fragment the inheritance as to render it too small to sustain the descendants at the socio-economic level of their forefather. Moreover, brothers and their descendants sometimes quarreled over their allocations, or even became estranged. While agnatic primogeniture became a common way of keeping the family's wealth intact and reducing familial disputes, it did so at the expense of younger sons and their descendants. Both before and after adoption of inheritance by primogeniture, younger brothers sometimes vied with older brothers to be chosen their father's heir or, after the choice was made, sought to usurp the elder's birthright (cf.Jacob and Esau).

Contents

In the parts of Europe where primogeniture prevailed, cadet sons were generally entitled to receive an appanage in patrimony, always substantially smaller than the eldest son's inheritance. Often, especially outside of Germany, the younger branch remained subordinate to the elder line as vassals or subjects.

In such cases, primary responsibility for promoting the family's prestige, aggrandizement, and fortune fell upon the senior branch for future generations. A cadet, having less means, was not expected to produce a family. If a cadet chose to raise a family, its members were expected to maintain the family's social status by avoiding derogation, but could pursue endeavors that might be considered demeaning for the senior branch, such as emigration to another sovereign's realm, or engagement in commerce, or a profession such as law, academia, or civil service.

A still more junior branch of the Wettins, headed by the rulers of the small Duchy of Saxe-Coburg and Gotha, would, through diplomacy or marriage in the 19th and 20th centuries, obtain the royal crowns of, successively, Belgium, Portugal, Bulgaria and the Commonwealth realms. Also, marriage to cadet males of the Houses of Oldenburg (Holstein-Gottorp), Polignac, and Bourbon-Parma brought those dynasties patrilineally to the thrones of Russia, Monaco, and Luxembourg, respectively. The Dutch royal house has, at different times, been a cadet branch of Mecklenburg and Lippe(-Biesterfeld). In the Commonwealth realms, Prince Philip, Duke of Edinburgh, and his male-line descendants are cadet members of the house of Glücksburg.

House of Guise; Although the Dukes of Lorraine exercised continental independence, nominally they were vassals of the Holy Roman Emperors and their geo-political importance resided less in the size of their realm than in their crucial location between the competing French and German nations. A younger brother of Duke Antoine, Claude of Lorraine, was appanaged with the lordship of Guise in France and betook himself to the French court in search of his fortune. There, he was granted the title Duke of Guise as a member of the Peerage of France, he and his male-line descendants henceforth being accorded the rank of prince étranger. As the Protestant Reformation threatened the unity of France the conspicuous loyalty of Claude's descendants to the Roman Catholic Church, combined with their barely concealed ambition upon the throne of the last Valois kings, infused the Guises with unequalled power in French politics. Their role in Paris and France's wars extended their influence in European affairs, until the accession of the House of Bourbon to the throne in 1593, far beyond that of their senior cousins reigning in Nancy.

Mandela: Nelson Mandela, the late president of the Republic of South Africa, was a male-line great-grandson of King Ngubengcuka of the Thembu nation of Southern AfricanXhosas. Be that as it may, he was, and fellow members of the Mandela branch of the Thembus' royal Madiba dynasty are, ineligible to succeed to the ancestral throne because they all descend from Ngubengcuka's morganatic marriage to a woman of a ritually inferior family. As such, their traditional role in the kingdom is that of hereditary privy counsellors to Thembu monarchs, unable to succeed to the throne themselves. In addition to this, the family's recognized leader also serves by tradition as the tribal chieftain of Mvezo under the authority of his relative the paramount chief of Thembuland, currently King Buyelekhaya Dalindyebo. Strictly speaking, however, the subordinate status of the Mandelas in relation to other descendants of the royal family is more due to their morganatic descent than to cadetship.

Wellington; Arthur Wellesley, the younger brother of Richard Wellesley, the 2nd Earl of Mornington, started his career as a protégé of his older brother. He entered the military, a traditional occupation of younger sons. From 1809 to 1814 he won a series of very significant victories, and was awarded a series of ascending titles; Baron Douro, Viscount Wellington, Earl of Wellington, Marquess of Wellington and, finally, Duke of Wellington. A descendant of Baron Cowley, youngest brother of Richard Wellesley, became Earl of Cowley in the Peerage of the United Kingdom, his junior line of the family thereby also achieving a higher status than that of the Earldom of Mornington in the Peerage of Ireland.